Hearing devices are wearable hearing apparatuses used to assist the hard-of-hearing. To meet the numerous individual requirements, different designs of hearing device are provided, such as behind-the ear (BTE) hearing devices, in-the-ear (ITE) hearing devices and concha hearing devices. The typical configurations of hearing device are worn on the outer ear or in the auditory canal. Above and beyond these designs however there are also bone conduction hearing aids, implantable or vibro-tactile hearing aids available on the market. In such hearing aids the damaged hearing is stimulated either mechanically or electrically.
Hearing devices principally have as their main components an input converter, an amplifier and an output converter. The input converter is as a rule a sound receiver, e.g. a microphone, and/or an electromagnetic receiver, e.g. an induction coil. The output converter is mostly implemented as an electroacoustic converter, e.g. a miniature loudspeaker, or as an electromechanical converter, e.g. bone conduction earpiece. The amplifier is usually integrated into a signal processing unit. This basic structure is shown in FIG. 1 using a behind-the ear hearing device as an example. One or more microphones 2 for recording the sound from the surroundings are built into a hearing device housing 1 worn behind the ear. A signal processing unit 3, which is also integrated into the hearing device housing 1, processes the microphone signals and amplifies them. The output signal of the signal processing unit 3 is transmitted to a loudspeaker or earpiece 4 which outputs an acoustic signal. The sound is transmitted, if necessary via a sound tube which is fixed with an otoplastic in the auditory canal, to the hearing device wearer's eardrum. The power is supplied to the hearing device and especially to the signal processing unit 3 by a battery 5 also integrated into the hearing device housing 1.
Hearing systems or hearing apparatuses worn on the ear are, as illustrated above, generally powered by means of a battery. As a result of the restricted service life of a battery, the system should be deactivated when it is not required. This is particularly the case when the system is removed from the ear.
A hearing system has, until now, conventionally been deactivated manually. With hearing devices, the battery compartment is generally opened for this purpose.
The publication EP 0 964 603 A1 discloses a method for automatically controlling a hearing device, in which method control parameters are continuously and dynamically generated at least as a function of the ambient noise. The generation of control parameters can be influenced by additional parameters such as the time of day, ambient temperature, ambient humidity and suchlike.
The patent application DE 10 2004 023 049 B4 also indicates a hearing apparatus having a switching arrangement for switching it on and off, with the switching arrangement including a resistance sensor for capturing an electrical volume-dependent load resistor. The hearing device can also include a temperature sensor, a pressure sensor or an acoustic sensor, in order to automatically detect its current state. If, for instance, it is being worn, an increased temperature or increased pressure can be measured. The state where the hearing device is in use can however also be recognized at the acoustic input level. The hearing device is automatically switched on or off as a function of the respective sensor signal and/or transferred into a standby mode.
The publications U.S. Pat. No. 4,955,729 A and US 2005/0254676 A1 disclose hearing devices which are automatically switched on and off with the temperature, pressure, resistance or an acoustic signal.
A hearing device is also known from patent application DE 37 42 529 C1, in which an acoustic feedback signal, an upper and lower temperature limit, the transition from a moved to an unmoved state or the oxygen partial pressure inside and/or outside of the auditory canal is used as the trigger criterion for the actuation of a switch acting on a change in state during removal of the hearing device from its position when in use. An acoustic feedback signal however only then results if the amplification of the hearing device is set sufficiently high. The acoustic path between the receiver and the microphone also determines, in a barely comprehensible fashion, the frequency and/or the frequency range of the whistling tone produced as a result of the feedback.